Under a black sun that gives no heat, Kostigrad is dug into the lip of a crater. Its people play for warmth. They throw bone dice in the pits, walk the wheel that turns the church domes, and lie in caps that carry them into a fairground of games. When they die, their finger-bones are carved into dice, so they can keep playing.

Fedya is the best loser on the Brim. Foremen hire him to lose to them in front of their families, and he makes every loss look real. Then the furnace in his honeycomb starts to fail. Ones, four hundred souls in the poorest square on the lip, is listed. After the Deal, the whole square will go into the caps for good, warm and smiling, until nobody is left in the cells to feel the cold.

At the Deal pit, the Brim's three-night dice tournament, the holder has not lost a final in twenty-two years. He offers Fedya the chair across from him and a warm room in a richer honeycomb. All Fedya has to do is lose, and he swears it on his pip. Then his neighbours carve slices off their tallies and bet them on him.

Now a new referee is reading the rulebook to the end. A soldier has come home to choose boys for the front. And a nine-year-old boy from Ones is climbing the board the soldier reads.

Kosti is the first book of Curse of the Tsars: a dark science fantasy of bone dice, a black sun and the price of losing well.